1. Field of the Invention
The present invention relates to a single-point bonding apparatus and more particularly to a single-point bonding apparatus that is equipped with a tool cleaning means.
2. Prior Art
Single-point bonding apparatuses are described in, for instance, Japanese Patent Application Laid-Open (Kokai) Nos. H4-24933, H8-153748 and H2-299247.
In these single-point bonding methods, the end portions of leads or the cut end portions of leads are connected respectively to pads by pressing the end portions or cut end portions of leads by means of a tool or a bonding tool. For this reason, the tip end of the tool is finely worked to a size of 125 xcexcm square or less.
A conventional single-point bonding method will be described with reference to FIGS. 3.
When a tool 14 is lowered in step (a) from a point above a lead 51 disposed on a tape 50 and the tool 14 contacts the end portion 51a of the lead 51, the tool 14 is in step (b) subsequently lowered more gradually than in step (a) while pressing the tip end of the lead 51 downward. Then, bonding is performed by application of pressure in step (c). In FIG. 3, the reference numeral 53 is a circuit board, 54 is a chip, and 55 is a pad.
Examples of conventional bonding apparatuses equipped with a tool cleaning means are described in, for instance, Japanese Patent Application Laid-Open (Kokai) Nos. H2-248055 and H7-321143. However, these apparatuses are wire bonding apparatuses being different from single-point bonding apparatuses.
The apparatus described in Japanese Patent Application Laid-Open (Kokai) No. H2-248055 uses a rotating polishing tape or grindstone as a cleaning means.
The apparatus described in Japanese Patent Application Laid-Open (Kokai) No. H2-248055 uses a rotating polishing tape or grindstone as a cleaning means. Accordingly, when the tool is to be cleaned, cleaning is accomplished by pressing the tip end of the tool against the polishing tape or grindstone.
The apparatus described in Japanese Patent Application Laid-Open (Kokai) No. H17-321143 is equipped with a cleaning liquid tank and an air nozzle installed on a cleaning stage as a cleaning means. When the tool is to be cleaned, the tip end portion of the tool is immersed in the cleaning liquid inside the cleaning liquid tank, an ultrasonic vibration is applied to the tool, and the tip end portion of the tool is then wiped clean by means of air that is blown out of the air nozzle while the tool is moving to the bonding stage.
In the above two prior arts, the tool that is cleaned is the tool of a wire bonding apparatus.
In Japanese Patent Application Laid-Open (Kokai) No. H2-248055, when the polishing tape or grindstone is pressed against the tool, the tip end of the tool may be damaged, or the useful life of the tool may be shortened. In particular, the tip end of the tool of a single-point bonding apparatus (which is the object of the invention of the present application) is finely worked to a size of 125 xcexcm square or smaller as described above. Accordingly, if the tool is pressed against a polishing tape or grindstone, or if the tool is immersed in a cleaning liquid and an ultrasonic vibration is applied to the tool, the tip end of the tool will break off so that the tool cannot be reused.
On the other hand, a method in which the tool is immersed in a cleaning liquid and an ultrasonic vibration is applied to the tool as in Japanese Patent Application Laid-Open (Kokai) No. H7-321143 is effective in cases where there is foreign matter adhering lightly to the tool. However, if such foreign matter adheres strongly to the tool, complete removal of the foreign matter is difficult. Furthermore, the use of a cleaning liquid requires a bothersome control process, and wiping of the tool by means of air causes problems in terms of scattering of the cleaning liquid so that the liquid adheres to surrounding parts of the mechanism. Moreover, provision of the necessary equipment results in excessive cost.
Accordingly, the object of the present invention is to provide a single-point bonding apparatus in which there is no damage to the tool, so that the tool can be used up to the end of its inherent life cycle and in which the operating efficiency of the apparatus is improved and the cost of the tool member is reduced.
The above object is accomplished by a unique structure for a single-point bonding apparatus that connects end portions of leads or cut end portions of leads to pads respectively by pressing such end portions of leads or cut end portions of leads with a tool; and in the present invention a cleaning stage which is used to clean the tool is additionally provided, and a cleaning chip is provided on a surface of the cleaning stage.
In the above structure, the cleaning stage is provided between a heating block and one of guide rails that guide a tape on which the leads are disposed, such one of guide rails being located on the bonding apparatus side; and gas jetting openings are formed in an upper surface of the cleaning stage, the gas jetting openings being located adjacent to the heating block.